Go up the stone platform, you'll see a short cut scene
of the mask, let the majin wait and go up the ladder
at the left, kill the enemy on this first bridge, open the treasure chest at the
end, jump back down to the majin.

(if you still haven't got the majin
knight achievement, you can do it in this area, walk in and out the area and fight
the enemies on the ground, the dog like creatures will jump on the majins back, slash them off and repeat until you've got the
achievement.)

Kill the enemies on the ground, from the entrance walk
to the left, all around the area until you see a treasure chest at the
left, an enemy on one of the bridges will throw fire bombs but if you're fast
enough he won't hurt you, go back to the entrance.

When you go to the right, you'll see a small area
behind some pillars, there is a shielded enemy and a mouse like creature, the majin can't get there so you'll have to fight them alone,
jump down and kill them (if you're
life is low, jump back up towards the majin and let
him refill your life), the memory
shard will be there in a corner when it's dark.

Past these pillars is another set of small pillars, go
behind them, to the right, open the treasure chest.

Turn the catapult towards the pillars you just came
from, you need to throw yourself on the left ledge behind those pillars, there
are some rocks to use in the catapult, throw some down and bring them to the
catapult.

Turn the catapult to the walls that need to be crushed
(to the right of the pillars), put a rock in the basket and crush the wall, select
the catapult again, climb in, fly to the glowing fire fruit and bring it back
to the majin.

Now all we need to get is the mask, turn the catapult
towards the NW corner so that you'll land on the bridge, don't bother with the
remaining enemy, just run to the mask and grab it.